The FDA has required that the labels of all carbidopa/levodopa-containing products (Crexont, Dhivy, Duopa, Rytary, Sinemet, Sinemet CR, Stalevo, Vyalev) include a warning about the risk of vitamin B6 (pyridoxine) deficiency and vitamin B6 deficiency-related seizures associated with their use. The combination of carbidopa/levodopa is the most effective treatment for the motor symptoms of Parkinson's disease and recent evidence favors its early use.

The FDA has approved Crexont (Amneal), an extended-release capsule formulation of carbidopa/levodopa, for treatment of Parkinson's disease (PD), postencephalitic parkinsonism, and parkinsonism associated with carbon monoxide or manganese intoxication. Crexont contains a combination of immediate-release carbidopa/levodopa granules and extended-release levodopa pellets. An extended-release carbidopa/levodopa oral capsule (Rytary) has been available from the same manufacturer for years; the patent for Rytary expires in 2025.

The motor symptoms of Parkinson's disease (PD) are caused primarily by degeneration of dopaminergic neurons in the substantia nigra. The nonmotor symptoms of the disease are thought to be caused by degeneration of other neurotransmitter systems. No disease-modifying drugs are available for treatment of PD.

View the Comparison Table: Drugs for Parkinson's Disease

The FDA has approved opicapone (Ongentys – Neurocrine), a peripherally-acting reversible catechol-O-methyltransferase (COMT) inhibitor, for oral use as an adjunct to carbidopa/levodopa in adults with Parkinson’s disease (PD) who experience "off" episodes. It is the third COMT inhibitor to be approved for this indication; tolcapone (Tasmar, and generics) and entacapone (Comtan, and generics) were approved earlier. Opicapone has been available in Europe since 2016.

The FDA has approved a sublingual fi lm formulation of the nonergot dopamine agonist apomorphine (Kynmobi – Sunovion) for acute, intermittent treatment of "off" episodes in patients with Parkinson's disease (PD). A subcutaneous formulation of apomorphine (Apokyn) has been available for years for the same indication in patients with advanced PD.

The FDA has approved istradefylline (Nourianz — Kyowa Kirin), an oral adenosine A_2A receptor antagonist, for use as an adjunct to carbidopa/levodopa in adults with Parkinson's disease (PD) who experience "off" episodes. Istradefylline is the first adenosine A_2A receptor antagonist to be approved in the US; it has been available in Japan since 2013.

The FDA has approved Inbrija (Acorda), an orally inhaled dry-powder formulation of levodopa, for intermittent treatment of "off" episodes in patients with Parkinson's disease (PD) being treated with carbidopa/levodopa (Sinemet, and others).

The motor symptoms of Parkinson's disease (PD) are caused primarily by degeneration of dopaminergic neurons in the substantia nigra. The nonmotor symptoms of the disease are thought to be caused by degeneration of other neurotransmitter systems.

View the Comparison Table: Drugs for Parkinson's Disease

The FDA has approved a new formulation of carbidopa/levodopa (Rytary – Impax) in extended-release capsules for treatment of Parkinson’s disease (PD).